1. Field of the Invention
Automobile drivers and operators of other dangerous equipment occasionally continue operation past the time when they should stop--when they are sleepy. This device is an alarm system to emit a wakening signal should the operator's head tilt. It is intended to improve the chances of equipment operators, and nearby persons, surviving an episode of sleep; thus is considered safety equipment of a specialized kind.
2. Description of Prior Art
A variety of devices for the purpose of awakening vehicle drivers has been proposed. The need has increased in recent years because long stretches of boring freeway have become more common, as has the use of trucks on long hauls. The use of tilting of the head to actuate the wakening alarm is customary, because the need to make the device easily attached and adjusted has been recognized in the art.
Except for Philians U.S. Pat. No. 3,054,868 which uses a chin plate switch attached to the clothing, the present art uses devices attached to a hat, to eyeglass bows, or more commonly to the ear. My use of the teeth to grip the device overcomes two problems which may have prevented widespread use of this type of device. First, the present invention is obviously easier and quicker to mount, which is an advantage in a dark car, while watching the road with the eyes and steering the car with one hand. Second, in using direct coupling to the bone structure it becomes possible to lower the necessary level of audible sounds, rendering the device less disturbing to other occupants of the vehicle. This is possible because the wearer receives some of the sensation of sound from vibration of the mouthpiece transmitted through the bone structure to his ear.
Most of the prior art relies on forward tilt of the head in one plane to close a normally-open mercury switch. Morrison U.S. Pat. No. 2,713,159 and Greene U.S. Pat. No. 3,076,186 include switches which will close if tilted in any plane, but no showing of operability for these switches was made. The present invention responds to tilt in any direction, and also reduces the cost of the switch by making it of fewer parts. The switch includes specific features developed by test to improve operation--specifically to reduce hysteresis.
In addition to making a head-tilt alarm easy to install, one should recognize the fact that the use of it will probably be very irregular, interrupted by months or years when it is simply kept inert, handy to the operator's seat. Thus operators are likely to forget how to activate and how to adjust the devices common in the prior art which have on-off switches or movable protrusions for adjusting the tilt angle setting at which the device actuates. The construction of my mercury switch has the advantage that merely turning the device upside down (inverting it) allows it to be stored for long periods with no drain on the battery. As the user erects it, the buzzer functions to confirm the battery is working, then stops when the silent zone is reached. The absence of a need to remember (or to re-learn by trial and error) how to use the device is an advantage over much of the prior art. The real object of this invention is to help save the lives of people who should not be driving, and minimizing the effect of their inebriation, confusion, or weariness could make an important contribution to that end.